Shock Absorber Having Unidirectional Fluid Flow

ABSTRACT

A twin-tube shock absorber comprising an outer tube which houses an inner tube. The inner tube forms an annulus area between the outer tube and the inner tube, and includes a check valve for allowing a fluid to flow unidirectionally from the annulus area to the interior volume of the inner tube. The shock absorber includes a piston which is slidably disposed within the inner tube and divides the interior volume into a rod side chamber and a cap side chamber. The piston includes a check valve allowing the fluid to flow unidirectionally from the cap side chamber to the rod side chamber. A flow regulator is disposed about the inner tube for allowing the unidirectional flow of fluid from the rod side chamber to the annulus area, wherein the flow regulator provides a resistance against the flow of the fluid from the rod side chamber to the annulus area.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application61/169,843, which was filed on Apr. 16, 2009, the entire disclosure ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a shock absorber. More particularly,the present invention pertains to a shock absorber having a twin tubeconstruction. Even more particularly, the present invention pertains toa twin tube construction shock absorber having unidirectional fluidflow.

2. Description of the Prior Art

Shock absorbers are well known in the art, such as found in U.S. Pat.No. 2,804,513 to Oppel; U.S. Pat. No. 5,588,510 to Wilke; U.S. Pat. No.6,648,109 to Farr et al.; U.S. Pat. No. 6,913,126 to Dohrmann et al.; aswell as U.S. Patent Publication No. 2002/0121416 to Katayama et al. Theshock absorbers disclosed by Oppel, Wilke, Farr, Dohrmann, and Katayamaare representative of the types of shock absorbers that are commonlyavailable. Such shock absorbers generally comprise a cylinder and apiston, the piston being connected to a rod which experiences a load.Fluid is contained within the cylinder. As the piston experiencescompression and rebound strokes, fluid is forced out of one side of thecylinder and fluid is forced into the other side through a series ofvalves. The valves may be disposed on the external portion of the shockabsorber. The shock absorber may also provide additional externalcomponents for controlling the flow of fluid from one side of thecylinder to the other, thereby controlling the damping force of theshock absorber.

However, such existing designs require a series of complex valvecomponents which can be expensive, difficult to maintain, and difficultto assemble. In addition, shock absorbers using this construction relyupon a series of valves to control the variability of the damping.Therefore, it is difficult to variably adjust the damping rate for theseshock absorbers.

Thus, there remains a need for a shock absorber which has a simplerconstruction, requires less moving parts, allows for easy adjustment ofthe damping force, and which preferably requires the same or less roomthan shock absorbers which are found in the prior art.

The present invention, as is detailed hereinbelow, seeks to resolvethese issues by providing a twin-tube construction shock absorber whichhas unidirectional fluid flow throughout the system and which comprisesa minimal number of moving parts, and which may additionally have thedamping force adjusted easily and/or remotely.

SUMMARY OF THE INVENTION

In a first embodiment hereof, the present invention provides aunidirectional twin-tube shock absorber which generally comprises:

-   -   (a) a cylindrically elongated outer tube having a first end and        a second end;    -   (b) a cylindrically elongated inner tube housed within the outer        tube, the inner tube having an interior surface, a first end,        and a second end which define an interior volume, the inner tube        forming an annulus area between the outer tube and the inner        tube, the inner tube having a check valve which allows a fluid        to flow unidirectionally from the annulus area to the interior        volume of the inner tube;    -   (c) a piston slidably disposed within the inner tube, the piston        having an outer circumferential surface dimensioned to form a        barrier against the interior surface of the inner tube, the        piston dividing the interior volume into a rod side chamber and        a cap side chamber, the piston having a piston check valve which        allows the fluid to flow unidirectionally from the cap side        chamber to the rod side chamber;    -   (d) a piston rod secured to the piston and extending outwardly        past the first end of the outer tube; and    -   (e) a flow regulator secured to the inner tube which allows        unidirectional flow of the fluid from the rod side chamber to        the annulus area, wherein the flow regulator provides a        resistance against the flow of the fluid from the rod side        chamber to the annulus area.

The flow regulator can comprise a valve seat and a spring disk fordirecting the flow of the first fluid from the rod side chamber to theannulus area. The valve seat is generally disk-like in shape and has agenerally circular outer circumferential edge and a central circularopening. The valve seat is preferably disposed about the first end ofthe inner tube and has the piston rod extending through the centralcircular opening. The valve seat comprises a plurality of orifice holesdisposed about the valve seat, the orifice holes being in fluidcommunication with the rod side chamber.

The spring disk can be provided for regulating the flow of the firstfluid from the orifice holes to the annulus area. The spring disk isgenerally disk-like in shape and has an inner circumferential edgedefining a central circular opening through which the piston rodextends. The spring disk also has an outer circumferential edge. Thespring disk is positioned over the valve seat and secured to the valveseat along the inner circumferential edge, wherein pressure from thefluid flowing through the orifice holes upwardly deflects the outercircumferential edge of the spring disk allowing the fluid to flow intothe annulus area.

The present invention can optionally include a piston rod intrusionmakeup area to compensate for volume taken up by the piston rod withinthe rod side chamber of the inner tube during compression. The pistonrod intrusion makeup area comprises a portion of the annulus area whichis filled with a compressible fluid, the compressible fluid preferablybeing a gaseous fluid, such as air or other gas. Alternatively, theintrusion makeup area may comprise a cylinder, which is housed eitherinternally or externally of the outer tube, and which is in fluidcommunication with the annulus area.

The intrusion makeup area operates to compensate for the additionalvolume consumed by the piston rod during a compression stroke. As thepiston rod enters the inner tube during a compression stroke, a volumeof the fluid is displaced out of the inner tube by the piston rod, andinto the annulus area. The intrusion makeup area compensates for thisadditional displacement by providing the compressible fluid which iscompressed under pressure from the fluid. As the compressible fluid iscompressed, it decreases in volume, thereby creating space for theincrease in volume of the fluid in the annulus area.

For a more complete understanding of the present invention, reference ismade to the following detailed description and accompanying drawing. Inthe drawing, like reference characters refer to like parts throughoutthe views in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view in cross-section of a first embodiment ofthe present invention hereof;

FIG. 2 is an enlarged perspective view in cross-section of the secondend of the present invention;

FIG. 3 is an enlarged perspective view in cross-section of the first endof the present invention;

FIG. 4 is an enlarged sectional view of the valve seat and spring diskassembly according to the present invention;

FIG. 5 is an enlarged section view wherein the flow regulator comprisesa valve seat, a pre-load seat, and an electromagnet;

FIG. 6 is an enlarged section view wherein the flow regulator comprisesa valve seat and a turbine; and

FIG. 7 is an enlarged cutaway sectional view showing the turbinearmature and a plurality of coil carriers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with a first embodiment of the present invention and asshown generally in FIGS. 1-4, there is provided a shock absorber 10having a twin tube construction. The shock absorber 10 comprises acylindrical elongated outer tube 12 having a first end 14 and a secondend 16. Although the first and second ends, 14 and 16, are preferablyopen, the first and second ends, 14 and 16, may be closed with a cap(not shown) after the internal components of the shock absorber 10 havebeen assembled therein. If cap ends are provided, they may be secured tothe outer tube 12 by means which are well known in the art, such as bywelding, crimping, threaded connection, or the like. The outer tube 12is formed from materials which are well known in the art for use withshock absorbers, including but not limited to, carbon steel, aluminum,stainless steel, composite materials, or the like. Although not shown,the second end 16 of the outer tube 12 preferably comprises means forsecurement to an object such as an axle or a vehicle frame.

The outer tube 12 houses on inner tube 18. The inner tube 18 comprises acylindrical elongated tube 19 having a first open end 22, a second openend 24, and an interior surface 23 which collectively define an interiorvolume 25. The inner tube 18 and the outer tube 12 are preferablysubstantially coaxially parallel with each other and define an annulusarea 20 therebetween. The inner tube 18 is formed from materials whichare well known in the art, including but not limited to, carbon steel,stainless steel, composite materials, or the like.

The inner tube 18 and the annulus area 20 are filled with a fluid 30.The fluid 30 may be either gaseous or liquid. Preferably, the fluid 30is a liquid such as oil. The type of fluid used may be any suitable typewhich is well known in the art for use with shock absorbers.

As shown in FIG. 2, the inner tube 18 also comprises a check valve 26located proximal to the second end 24 thereof. The check valve 26 placesthe annulus area 20 and the interior volume 25 of the inner tube 18 influid communication, and allows the fluid 30 to flow from the annulusarea 20 into a cap side chamber 28 of the inner tube 18, as discussed infurther detail below. Any suitable type of check valve which is wellknown in the art may be used, including but not limited to, a ball andspring check valve, such as found in U.S. Pat. No. 3,343,564 to Peepleset al., or a deflected disk check valve, such as found in U.S. Pat. No.2,223,944 to Roy. Preferably, a deflected disk check valve is usedbecause it has flow and pressure drop characteristics which aredesirable for application in the present invention.

As seen in FIG. 3, the inner tube 18 houses a piston 32. The piston 32is generally disk-like in shape and has an outer circumferential surface34. The piston 32 is dimensioned such that the outer circumferentialsurface 34 of the piston 32 is juxtaposed the inner surface 23 of theinner tube 18, thereby forming a substantially fluid-tight barrierbetween the inner tube 18 and the piston 32. The piston 32 is capable ofsliding to and fro along an axis of the inner tube 18, and divides theinterior volume of the inner tube 18 into two separate chambers, namely,a rod side chamber 38 and a cap side chamber 28.

The outer circumferential surface 34 of the piston 32 may include arecess 40 extending thereabout for housing a seal 42, such as an O-ringor any other suitable type of seal. The seal 42 assists in forming thebarrier between the piston 32 and the inner tube 18. The seal 42 alsoacts as a bearing between the inner tube 18 and the piston 32. The seal42 is formed from materials which are well known in the art, includingbut not limited to, polymers such as plastics or elastomers.

The piston 32 additionally comprises a check valve 44. The check valve44 is of similar type as discussed above, and may be placed atop thepiston 32 or retained within the piston 32. The piston check valve 44places the cap side chamber 28 and the rod side chamber 38 in fluidcommunication, such that the fluid 30 may flow from the cap side chamber28, through the piston check valve 44, and into the rod side chamber 38.

A piston rod 46 is provided which is secured to the piston 32. Thepiston rod 46 is substantially coaxially aligned with the inner tube 18,and extends outwardly from the piston 32 toward the first end 14 of theouter tube 12. The piston rod 46 extends through a central circularopening 48 of a valve seat 50 and through a rod side seal carrier 52,which are discussed in further detail below. The piston rod 46 has adistal end 54 which extends outwardly past the first end 14 of the outertube 12. The distal end 54 of the piston rod 46 preferably includesmeans for securement (not shown) to an object (not shown), such as anaxle or frame of a vehicle. The means for securement may include anysuitable means which are well-known in the art, such as a bracket,clamp, and so forth.

Referring back to FIG. 1, the outer tube 12 houses the rod side sealcarrier 52 and a cap side seal carrier 56. Each of the seal carriers52,56 is located at its respective end of the outer tube 12. Each sealcarrier 52,56 is substantially cylindrical in shape and dimensioned tobe insertable into the outer tube 12. The seal carriers 52,56, areprovided to support and seal the internal components of the shockabsorber 10. Each seal carrier 52,56 comprises a plurality of seals58,58′, etc. for preventing fluid 30 from exiting the outer tube 12.Each seal carrier, 52 and 56, has at least one annular recess 60,60′,etc. encircled about an outer circumferential surface 62,62′, and atleast one of the seals from the plurality of seals 58,58′, etc. isdisposed in each recess 60,60′, etc. to seal the surface interfacebetween the seal carriers 52,56 and the outer tube 12.

Each seal carrier 52,56 is formed from suitable materials which arenon-porous and have desirable temperature and strength characteristicsenabling them to last a long time, such as a metal (e.g. aluminum,brass, steel, etc.) or a polymer (e.g. nylon). Preferably the sealcarriers 52,56 are made from steel.

Furthermore, each seal carrier 52,56 is secured within its respectiveend of the outer tube 12 by suitable means which are well known in theart. For instance, each seal carrier 52,56 may be press fit into theouter tube 12. Additionally the outer circumferential surface 62,62′ ofeach seal carrier 52,56 and the inner surface 64 of each end of theouter tube 12 may be threaded for threaded interengagement with eachother. As such, each seal carrier 52,56 may be threadably secured withinits respective end of the outer tube 12.

It is to be understood by one having ordinary skill in the art that ifan outer tube 12 is provided which has a closed second end 16, then thecap side seal carrier 56 is not required in order to seal the outer tube12.

As shown in FIGS. 1 and 3, the rod side seal carrier 52 also comprisesan inner circular through-hole 66 which is dimensioned to retain thepiston rod 46. The inner circular through-hole 66 comprises at least oneannular recess 68 to retain a seal 70 for sealing the surface interfacebetween the rod side seal carrier 52 and the piston rod 46. The seals 70and 58,58′, etc. used for sealing the seal carriers 52,56 are formedfrom materials which are well known in the art, including polymers suchas plastics or elastomers.

In addition, the through-hole 66 of the rod side seal carrier 52 has abearing surface 72 for maintaining the piston rod 46 in alignment withthe inner and outer tubes, 14 and 12, respectively. The bearing surface72 is preferably a linear bearing of the type which is well-known in theart. Even more preferably, the linear bearing comprises a plane bearinghaving a bearing surface made of polytetrafluoroethylene, which iscommonly sold under the trademark Teflon®. Alternatively, the linearbearing may be a roller-type bearing having a plurality of recirculatingball bearings.

In use, the piston rod 46 is configured to be secured to a first object(not shown), such as the frame of a vehicle, and the outer tube 12 ofthe shock absorber 10 is configured to be secured to a second object(not shown), such as the axle of a vehicle. When the first and secondobjects move relative to each other, the piston 32 and piston rod 46move relative to the inner and outer tubes 14,12 of the shock absorber10. It is thus seen that the piston 32 and piston rod 46 slidably moverelative to the inner tube 18 during operation of the shock absorber 10.

Referring back to the internal components of the shock absorber 10 asshown in FIG. 4, a flow regulator 49 is provided for directing the fluid30 to flow from the rod side chamber 38 to the annulus area 20. The flowregulator 49 can comprise a valve seat 50 and at least one spring disk80. The valve seat 50 is generally disk-like in shape and is securedabout the first end 22 of the inner tube 18. The valve seat 50 has acentral circular opening 48 through which the piston rod 46 extends. Thevalve seat 50 comprises a plurality of orifice holes 76,76′, etc. Theorifice holes 76,76′, etc. extend through the valve seat 50 such thatthe rod side chamber 38 of the inner tube 18 is placed in fluidcommunication with the area atop the valve seat 50. The orifice holes76,76′, etc. are disposed about the valve seat 50, preferably in anevenly-spaced array. The valve seat 50 further comprises a raised ridge,or land seat 78, which extends about the outermost circumferential edgeof the valve seat 50. The land seat 78 can include notches for bleedinga minimal flow of fluid 30 past the valve seat 50, as will be betterunderstood by the following discussion.

At least one spring disk 80 can be provided for regulating the flow offluid 30 through the orifice holes 76,76′, etc. and into the annulusarea 20. The at least one spring disk 80 comprises a generally circulardisk which is substantially planar or flat and is capable of beingdeflected. The spring disk 80 has an outer edge 82, a central circularopening 84, and an inner edge 86. The inner edge 86 encircles the pistonrod 46. The spring disk 80 is positioned over the valve seat 50 such asshown in FIG. 4. The inner edge 86 is secured to the valve seat 50 in amanner which is described in further detail below. The outer edge 82 ofthe spring disk 80 sits atop, or abuts the land seat 78 of the valveseat 50.

In operation, pressurized fluid 30 flows up through the orifice holes76, 76′, etc. and applies an upward force against the bottom side of thespring disk 80. The spring disk 80 is deflected about the secured inneredge 86, thereby creating a gap between the outer edge 82 of the springdisk 80 and the land seat 78 through which the fluid 30 flows. Theamount of pressure, or force, required to deflect the spring disk 80(and allow the fluid 30 to flow) is commonly known in the art as the“blow off” pressure.

If more than one spring disk 80 is provided, then the plurality ofspring disks 80 may be stacked together. In such an arrangement, eachspring disk 80 from the plurality of spring disks 80 may have aconsistent nominal thickness, such that adjusting the number of springdisks used may be a parameter employed for adjusting the blow offpressure.

The spring disk 80 is formed from any suitable material known in theart, including metals such as spring steel, and in particular, bluetempered spring steel. It is understood to those having ordinary skillis in the art that the material used should have a high yield strengthso that the spring disk 80 does not experience plastic deformation. Itis also understood by one of ordinary skill in the art that the type ofmaterial chosen for the spring disk 80, and its corresponding materialproperties, such as elasticity and strength, are a factor in determiningthe amount of force generated for any given velocity.

As shown in FIG. 4, the inner edge of the spring disk 80 is securedbetween the rod side seal carrier 52 and the valve seat 50 by aplurality of shims 88. At least one shim 88 can be positioned below andabove the spring disk 80. The shims 88 and the spring disk 80 areclamped tightly between the rod side seal carrier 52 and the valve seat50, thereby securing the inner edge 86 of the spring disk 80 inposition. The quantity and thickness of the shims 88 used determines theshim height, which is designated as x in FIG. 4. For any particularspring disk thickness, as the shim height x decreases, the blow offpressure increases. The shims 88 are formed from suitable materialswell-known in the art, including, carbon steel. It is to be appreciatedby one having ordinary skill in the art that the shim height is one ofseveral factors relevant to determining the blow off pressure. It isalso to be understood by those having ordinary skill in the art thatassembling the spring disk 80 and shims 88 in a manner which requires aforce to deflect the spring disk 80 away from the land seat 78 isreferred to as “preloading.”

The rod side seal carrier 52, valve seat 50, spring disk 80, and shims88 may be assembled together by a number of suitable methods.Preferably, the valve seat 50 is placed into the outer tube 12 (sittingatop the inner tube 18), and at least one shim 88 is placed over thevalve seat 50. The spring disk 80 is then placed atop the at least oneshim 88. At least one additional shim 88 is then placed over the springdisk 80. The rod side seal carrier 52 is then placed over the valve seat50, spring disk 80, and shims 88. The rod side seal carrier 52 issecured in position, thereby securing the valve seat 50, inner edge 86of the spring disk 80, and shims 88 in position. Alternatively, anassembly of the rod side seal carrier 52, shims 88, spring disk 80, andvalve seat 50 may be press fit together, and assembled into the shockabsorber 10 as an assembled unit.

In a further alternate method of assembly, the valve seat 50 and rodside seal carrier 52 may be provided with corresponding threadedsurfaces such that the shims 88 and spring disk 80 may be assembled ontothe valve seat 50, and the rod side seal carrier 52 and valve seat 50may then be threadably secured to each other. The entire threadedassembly may then be inserted into the shock absorber 10. Otherwise, thethreaded valve seat 50, shims 88, and spring disk 80 may be insertedinto the shock absorber 10 and the threaded rod side seal carrier 52 maythen be threadably secured to the threaded valve seat 50.

The present invention may also provide a piston rod intrusion makeuparea 90 to compensate for volume taken up by the piston rod 46 withinthe inner tube 18 during a compression stroke. During a compressionstroke, the piston rod 46 enters the inner tube 18, thereby taking up anincreasing amount of volume within the inner tube 18. Since the innertube 18 has a finite interior volume, a piston rod intrusion makeup area90 may be provided to compensate for the increase in volume of thepiston rod 46. The piston rod intrusion makeup area 90 contains a volumeof compressible fluid 91 and is in fluid communication with the annulusarea 20. Preferably the intrusion makeup area 90 is located within theannulus area 20, however, it can be positioned in any other suitablelocation, even including outside the shock absorber 10 itself.

The intrusion makeup area 90 can optionally include a fluid separator 93to isolate the fluid 30 and the compressible fluid 91 from mixing witheach other during operation. As understood by one of ordinary skill inthe art, mixing of the two fluids is undesirable, particularly when thefluid 30 is a liquid and the compressible fluid 91 is a gas. The fluidseparator 93 can comprise a flexible membrane (e.g., membrane formedfrom a flexible polymer such as an elastomer), a floating physicalbarrier (e.g., a floating disc or cylinder), or any other suitable meansfor isolating the fluids from each other to minimize or eliminateintermixing.

In operation, as the piston rod 46 enters the inner tube 18, fluid 30 isdisplaced by the piston rod 46 and forced into the annulus area 20. Asthe fluid 30 becomes pressurized, it compresses the compressible fluid91 in the intrusion makeup area 90, thereby allowing the fluid 30 toexpand into a portion of the intrusion makeup area 90. The compressiblefluid 91 housed in the intrusion makeup area 90 may be air or a gas,such as nitrogen, xenon, or the like. The compressible fluid 91 may beat atmospheric pressure or it may be pressurized. Preferably, thecompressible fluid 91 is either air (at either atmospheric pressure orcompressed) or compressed nitrogen. It may also be possible that thecompressible fluid 91 comprises a closed cell foam rather than a gaseousfluid in situations where aeration or cavitation occurs.

The present invention can optionally provide means for diverting fluidflow 94 from the valve seat 50 into the annulus area 20. The means fordiverting fluid flow 94 can be provided to assist the fluid flow frombecoming turbulent as it exits the valve seat 50. The means fordiverting fluid flow 94 may comprise a curved disk, a downwardlypointing vent, or any other suitable means which are well-known in theart. The flow of the fluid 30 is preferably laminar as it exits thevalve seat 50 so that it does not become aerated or experiencecavitation.

In use, the shock absorber 10 is continuously experiencing compressionand rebound strokes. In a typical shock absorber, fluid moves in abidirectional flow back and forth from one side of the piston to theother, as well as in and out of a rod intrusion makeup area connected tothe rod side chamber. However, in the present invention, the fluid 30flows unidirectionally regardless of whether the shock absorber 10 isexperiencing a compression or rebound stroke, as discussed below.

According to the present invention, during a compression stroke thepiston 32 is forced downward by the piston rod 46. The check valve 44 inthe piston 32 allows the fluid 30 to flow from the cap side chamber 28to the rod side chamber 38. The inner tube check valve 26 does not allowthe fluid 30 in the cap side chamber 28 to exit through the inner tubecheck valve 26. However, as the piston rod 46 enters the inner tube 18,it consumes an increasing amount of volume within the inner tube 18,thereby forcing that same volume of fluid 30 out of the rod side chamber38, through the orifice holes 76,76′, etc., past the spring disk 80, andinto the intrusion makeup area 90. It is thus seen that during thecompression stroke, the force required to deflect the spring disk 80 andthe force required to compress the compressible fluid 91 in theintrusion makeup area 90 collectively provide a damping force to thepiston rod 46.

During the rebound stroke, the piston 32 and the piston check valve 44force fluid 30 out of the rod side chamber 38, through the orifice holes76,76′, etc., past the deflected spring disk 80, and into the annulusarea 20. As the piston rod 46 exits the inner tube 18, the piston rod 46itself consumes less volume, and the fluid 30 exits the intrusion makeuparea 90. As the fluid 30 is forced into the annulus area 20, it flowsthrough the inner tube check valve 26, and into the cap side chamber 28of the inner tube 18. It is noted that, since the fluid 30 is containedwithin a sealed system, the piston 32 also creates a vacuum in the capside chamber 28 during rebound, thereby contemporaneously drawing thefluid 30 into the cap side chamber 28. During rebound, the spring disk80 provides the damping force to the shock absorber 10.

It is thus seen that, as the shock absorber 10 repetitively experiencescompression and rebound, the fluid 30 continues to flow up from the capside chamber 28 to the rod side chamber 38, through the orifice holes76,76′, etc., past the deflected spring disk 80, into the annulus area20, through the inner tube check valve 26, and once again into the capside chamber 28 of the inner tube 18.

As shown in FIG. 5, in addition to the valve seat 50 and the spring disk80, the flow regulator 49 can optionally include a pre-load seat 112and/or an actuator 114. The pre-load seat 112 is juxtaposed a topsurface 92 of the spring disk 80. The pre-load seat 112 is preferablygenerally circular in shape. Preferably, the pre-load seat 112 issecured to the spring disk 80, and can be formed from a magneticmaterial. The pre-load seat 112 is concentrically positioned over thespring disk 80 and may be dimensioned to contact the spring disk 80 at aparticular radial length from the center point of the spring disk 80. Itis thus seen that by varying the radial contact position between thepre-load seat 112 and the spring disk 80, the mechanical advantage ofthe pre-load seat 112 over the spring disk 80 may by variably adjusted.Furthermore, the spring disk 80 can optionally have an oversizeddiameter such that the outer circumferential edge of the spring disk 80may extend beyond the land seat 78, and the pre-load seat 112 can bepositioned over the spring disk 80 at a radial position outside the landseat 78, thereby giving the pre-load seat 112 a further mechanicaladvantage.

It is also appreciated that the radial position of the pre-load seat 112on the spring disk 80 is yet another factor which contributes to theresulting damping force of the shock absorber 10.

The actuator 114 can be provided for applying a force to the pre-loadseat 112. The actuator 114 is preferably any suitable type ofelectro-mechanical device, such as the type including an electromagnet,for example, a solenoid. The actuator 114 is configured to receiveelectrical current from a source such as a battery or an alternator.Means for connecting 116 the actuator 114 to each pre-load seat 112 canbe provided such that, by conducting electricity through the actuator114, the actuator 114 applies a force to the pre-load seat 112, which inturn, applies that force to the top surface 92 of the spring disk 80.The means for connecting 116 may comprise a rod, coil, spring, or thelike. In addition, the pre-load seat 112 may be formed from a magneticmaterial, such that a magnetic force may be applied to the pre-load seat112 by the actuator 114. It is thus seen that, by varying the electricalcurrent through an actuator 114, the resulting force applied to thespring disk 80 is proportionately varied. It is noted that the forceapplied to the spring disk 80 by the actuator 114 can be either anupward or downward force. As such, the amount of force required todeflect the spring disk 80 can be controlled by electro-mechanicalmeans, so long as the spring disk 80 remains secured to the actuator114.

It is to be understood by one having ordinary skill in the art that,according to this arrangement, the blow off pressure is equal to thepreload force of the spring disk 80 against the land seat 78 plus theamount of force applied onto the top surface 92 of the spring disk 80 bythe actuator 114. Therefore, in such an embodiment, it may be possibleto reduce the preload force of the spring disk 80 such that the blow offpressure is substantially equal to the amount of downward force appliedby the actuator 114.

The means for connecting 116 can also apply an upward force on thespring disk 90. As such, the actuator 114 and means for connecting 116can be configured to decrease the blow off pressure when theelectromagnetic 114 applies an upward force to reduce the damping forcefor effectively creating a “negative” blow off pressure. The means forconnecting 116 can compromise any suitable component well-known in theart, such as a rod or other suitable member secured to the actuator 114and the spring disc 90.

Means for controlling 118 the flow regulator 49 can also be provided tomonitor and adjust the force required to deflect the spring disk 80. Themeans for controlling 118 the flow regulator 49 can comprise anysuitable type of control system, such as a computer or logic controlsystem which can monitor and supply the actuator 114 with the correctamount of electricity to adjust the blow off pressure accordingly. Forexample, in use with a vehicle, the vehicle's computer system, or chip,may provide information related to preferred damping rates whichdetermines how much force is necessary to deflect the spring disk 80. Assuch, the vehicle's computer is configured to remotely control thedamping force at each shock absorber 10. With regard to this aspect, themeans for controlling 118 can be configured to provide variable settingsdependent upon vehicle speed, g-forces experienced by the vehicle, roadconditions, weather conditions, and so forth. The means for controlling118 can also be configured to have various pre-settings which may bemanually selected so that the user of the vehicle may choose aparticular setting dependent upon driving style, personal preference,weather conditions, and so forth.

Furthermore, the means for controlling 118 is capable of instantaneouslychanging the damping force at each shock absorber 10 to adjust tochanging road conditions. For example, during vehicle acceleration ordeceleration, the means for controlling 118 may increase or decrease thedamping force at each individual shock absorber 10 to minimize nose dipor rise of the vehicle. In addition, the means for controlling 118 iscapable of instantly adjusting the damping force during tight corneringto increase ride stability and comfort in the vehicle cabin. It is to beappreciated that the damping settings may be changed by the means forcontrolling 118 as quickly as electrical current can run through thesystem.

As shown in FIGS. 6 and 7, in yet another configuration, the flowregulator 49 can comprise the valve seat 50 and at least one turbine 214which is configured to be driven by flow of the fluid 30 through theplurality of orifice holes 76,76′, etc. It is to be understood that suchan embodiment is possible because the flow of fluid 30 through theorifice holes 76,76′, etc. is unidirectional.

In this arrangement, the valve seat 50 can optionally include a collar220 extending about the outer edge of the valve seat 50. The collar 220can include a plurality of outlets 222, which are discussed in furtherdetail below.

The turbine 214 includes a rotating, or spinning, armature 216 securedover the valve seat 50 in place of the spring disk. The armature 216includes a disc, or ring-like, shaped magnet 218 secured thereon whichrotates with the armature 216. The magnet 218 is preferably a permanentmagnet.

The lower surface 228 of the armature 216 includes an annular recess 224which receives the fluid 30 passing through the orifice holes 76,76,etc. The armature 216 also includes a plurality of vanes, or angledpassages, 226 disposed about the lower surface 228 and in fluidcommunication with the annular recess 224. The armature 216 ispositioned over the valve seat 50 such that the orifice holes 76,76′,etc. are juxtaposed the annular recess 224. It is thus seen that thefluid 30 flows through the orifice holes 76,76′, etc., into the annularrecess 224, through the plurality of angled passages 226, and out theplurality of outlets 222 on the collar 220.

In use, the fluid 30 flows through the orifice holes 76,76′, etc. andapplies a rotational force against the plurality of angled passages 226,thereby rotating the armature 216 and magnet 218. It is preferred thatthe plurality of angled passages 226 and plurality of outlets 222 bedimensioned and arranged (i.e., by the quantity of and/or geometry ofthe passages and/or outlets) to operate together such that the fluid 30always has at least one aligned passage/outlet pair to allow the fluid30 to flow therethrough so that the armature will not experience staticlock. Preferably the plurality of angled passages 226 and the pluralityof outlets 222 are dimensioned and arranged to spin the armature 216 andmagnet 218 with maximum efficiency and/or to provide preferred dampingcharacteristics to the shock absorber 10.

The armature 216 in secured in place and rotates along a plurality ofbearings 230, or other suitable means for rotatably mounting whichprovide a negligible amount of rotational resistance due to structuralimpediments. It is desired that as much energy be converted intoelectricity as possible. It is noted that the plurality of bearings 230and the armature 216 provide a seal with the inner tube 18 to preventthe fluid 30 from escaping.

The flow regulator also includes a plurality of coil carriers 232disposed about the inner tube 18 and positioned proximate to the magnet218. Each of the coil carriers 232 comprises coiled rods or any othersuitable structure for generating electricity as a result of theelectromagnetic field created by the spinning magnet 218.

When the flow regulator 49 comprises a turbine 214 and a plurality ofcoil carriers 232, it is to be appreciated that the force required torotate the armature 216 provides the damping force by providingresistance to the flow of the fluid 30 throughout the shock absorber 10.Therefore, the damping of the shock absorber 10 may be variably adjustedby adjusting the electrical load applied to the armature 216 by theplurality of coil carriers 232. It is to be understood that theelectricity which is generated can either be stored or fed back into thevehicle's electrical system.

The means for controlling 118 the flow regulator 49 can be provided tocontrol the turbine 214 in this embodiment as well. For instance, themeans for controlling 118 can control the damping rate of the shockabsorber 10 by adjusting the electrical load on the turbine, which inturn, adjusts the amount of force necessary to rotate the armature 216.

It is to be appreciated that this arrangement is not limited in scope tothe specific description herein. The present invention may be outfittedwith at least one turbine according to any suitable structuralarrangement which allows the armature to be driven by fluid flowingthrough the shock absorber.

It is to be understood that the present invention is not limited to thespecific aspects described above. The shock absorber may comprise any orall combinations of the disclosed embodiments. In addition, the presentinvention is not limited to any specific material types, and it iscontemplated that the present invention embodies any materials which maybe suitable for use herewith.

It is to be appreciated that the flow regulator can be interchanged witheither of the check valves, and that the flow regulator need notspecifically restrict the flow of fluid from the inner tube to theannular area as described in the exemplary embodiment above.

It is to be further understood that the valve seat and spring disk, asoperably discussed herein, may be used for other applications in whichflow rate and/or pressure through an orifice need be controlled. Forinstance, the valve seat and spring disk may be used in pressure controlvalves to control the pressure and flow through the orifice holes. Justas described above, an electromagnet or a turbine may be used to controlthe flow and/or pressure through a valve, as well as to reclaim kineticenergy into electrical energy.

It is to be further appreciated by one of ordinary skill in the art thatone of the benefits of the present invention is that it provides aself-bleeding shock absorber. For instance, if there is a volume of aircontained within either the cap side or rod side chambers, it will workits way through the system as the shock absorber experiences compressionand rebound strokes until it flows though the shock absorber and intothe makeup intrusion area.

An additional benefit of the present invention is that a fluid filtermay be installed within the shock absorber. Because the fluidexperiences unidirectional flow, it is possible to install a filter inthe fluid path so as to filter contaminants out of the fluid during use.It is to be appreciated by one having ordinary skill in the art thatsuch a feature is not easily possible for use in a shock absorber havingbidirectional fluid flow.

It is further contemplated that a benefit of the present invention is amore uniform temperature gradient throughout the shock absorber thanshock absorbers which exist in the prior art. Because the shock absorberhas a unidirectional fluid flow, the continuously flowing fluid assistsin transferring heat from the outer tube to the inner tube, therebyproviding a shock absorber having a more uniform temperature gradient.It is appreciated by one of ordinary skill in the art that structuralfailure due to, or accelerated by, extreme temperatures will besignificantly reduced due to the present invention's inherent ability toevenly distribute heat throughout the shock absorber.

It is also understood that the shock absorber disclosed herein may beused with, or on, any suitable apparatus which has components thatexperience relative motion, and for which it may be desirable to dampenthe movement therebetween. Therefore, present intention is not limitedto use only on vehicles.

As is apparent from the preceding, the present invention provides ashock absorber having a twin tube construction with unidirectional fluidflow which provides a simple construction with minimal parts, and whichmay have the damping force instantaneously varied very easily andremotely.

1. A shock absorber comprising: a cylindrically elongated outer tubehaving a first end and a second end; a cylindrically elongated innertube housed within the outer tube, the inner tube having an interiorsurface, a first end, and a second end which define an interior volume,the inner tube forming an annulus area between the outer tube and theinner tube, the inner tube having a check valve which allows a fluid toflow unidirectionally from the annulus area to the interior volume ofthe inner tube; a piston slidably disposed within the inner tube, thepiston having an outer circumferential surface dimensioned to form abarrier against the interior surface of the inner tube, the pistondividing the interior volume into a rod side chamber and a cap sidechamber, the piston having a piston check valve which allows the fluidto flow unidirectionally from the cap side chamber to the rod sidechamber; a piston rod secured to the piston and extending outwardly pastthe first end of the outer tube; and a flow regulator secured to theinner tube which allows the unidirectional flow of the fluid from therod side chamber to the annulus area, wherein the flow regulatorprovides a resistance against the flow of the fluid from the rod sidechamber to the annulus area.
 2. The shock absorber of claim 1 whereinthe flow regulator comprises a valve seat and a spring disk, the valveseat being substantially disk-like in shape and having a substantiallycircular outer circumferential edge including a raised land seatextending thereabout, the valve seat including a central circularopening having the piston rod extending therethrough, the valve seatcomprising a plurality of orifice holes extending through the valve seatand being disposed thereabout, the orifice holes being in fluidcommunication with the rod side chamber; and the spring disk beingsubstantially disk-like in shape and having an inner circumferentialedge defining a central circular opening having the piston rod extendingtherethrough, and an outer circumferential edge, the spring disk beingpositioned atop the valve seat and secured to the valve seat along theinner circumferential edge, the outer circumferential edge beingjuxtaposed the land seat, wherein the fluid flowing through the orificeholes forces the outer circumferential edge of the spring disk todeflect away from the land seat, thereby allowing the fluid to flow intothe annulus area.
 3. The shock absorber of claim 2 wherein the innercircumferential edge is positioned between at least a pair of shims suchthat the number of shims placed on each side of the innercircumferential edge varies the position of the inner circumferentialedge with respect to the outer circumferential edge which is abuttedagainst the land seat, thereby adjusting the amount of force required todeflect the spring disk.
 4. The shock absorber of claim 3 comprising arod intrusion makeup area containing a volume of compressible fluid. 5.The shock absorber of claim 4 wherein the rod intrusion makeup areaincludes a fluid separator for isolating the fluid from the compressiblefluid.
 6. The shock absorber of claim 2 comprising a rod intrusionmakeup area containing a volume of compressible fluid which is in fluid.7. The shock absorber of claim 6 wherein the rod intrusion makeup areaincludes a fluid separator for isolating the fluid from the compressiblefluid.
 8. The shock absorber of claim 2 wherein the flow regulatorcomprises a pre-load seat secured to the spring disk, and anelectromagnet in operable connection with the pre-load seat, whereinsupplying the electromagnet with electricity applies a force to thepre-load seat and the spring disk.
 9. The shock absorber of claim 8comprising means for controlling the flow regulator to monitor andadjust the force required to deflect the spring disk by adjusting theflow of electricity to the electromagnet.
 10. The shock absorber ofclaim 9 comprising a rod intrusion makeup area containing a volume ofcompressible fluid.
 11. The shock absorber of claim 10 wherein the rodintrusion makeup area includes a fluid separator for isolating the fluidfrom the compressible fluid.
 12. The shock absorber of claim 8comprising a rod intrusion makeup area containing a volume ofcompressible fluid.
 13. The shock absorber of claim 9 wherein the rodintrusion makeup area includes a fluid separator for isolating the fluidfrom the compressible fluid.
 14. The shock absorber of claim 1 whereinthe flow regulator comprises a valve seat and a turbine, the valve seatbeing substantially disk-like in shape and having a substantiallycircular outer circumferential edge and including a central circularopening having the piston rod extending therethrough, the valve seatcomprising a plurality of orifice holes extending through the valve seatand being disposed thereabout, the orifice holes being in fluidcommunication with the rod side chamber; and the turbine beingpositioned atop the valve seat and having an armature and a stator, thearmature including a plurality of vanes which are driven by the flow ofthe fluid through the orifice holes.
 15. The shock absorber of claim 14comprising means for controlling the flow regulator to monitor andadjust the force required to rotate the armature of the turbine.
 16. Theshock absorber of claim 15 comprising a rod intrusion makeup areacontaining a volume of compressible fluid.
 17. The shock absorber ofclaim 16 wherein the rod intrusion makeup area includes a fluidseparator for isolating the fluid from the compressible fluid.
 18. Theshock absorber of claim 14 comprising a rod intrusion makeup areacontaining a volume of compressible fluid.
 19. The shock absorber ofclaim 18 wherein the rod intrusion makeup area includes a fluidseparator for isolating the fluid from the compressible fluid.
 20. Ashock absorber having an outer tube containing an inner tube, a fluidwhich flows unidirectionally through each of the tubes, and aunidirectional flow regulator which provides resistance against flow ofthe fluid from one of the tubes to the other.